Figure 6. All inputs examined are drivers.
(A) Representative current clamp recordings of motor thalamic neuron demonstrating distal activation of layer 5 of primary motor cortex (M1L5) axons (>300 μm from recorded cell) gives a depressing response at low (10 Hz, left) and high frequencies (40 Hz, right) that is insensitive to metabotropic glutamate receptor (mGluR) antagonists (40 μM LY367385 and 30 μM MPEP) but abolished by DNQX. (B) Representative current clamp recordings of motor thalamic neuron demonstrating distal activation of cerebellar nuclei (Cb) axons (>300 μm from recorded cell) gives a depressing response at low (10 Hz, left) and high frequencies (40 Hz, right) that is insensitive to mGluR antagonists (40 μM LY367385 and 30 μM MPEP) but abolished by DNQX. (C) Representative current clamp recordings of motor thalamic neuron demonstrating distal activation of internal segment of the globus pallidus (GPi) axons (>300 μm from recorded cell) gives a depressing response at low (10 Hz, left) and high frequencies (40 Hz, right) that is insensitive to GABAB antagonists (CGP 46381, 25 μM) but abolished by gabazine (20 μM). (D) Compiled paired-pulse ratio (PPR) (second EPSC/first EPSC) data for all cells recorded receiving only the input of interest (not mixed inputs) plotted according to the amplitude of the first EPSC. PPRs below 1.0 (dotted line) are considered depressing, while those above 1.0 are considered facilitating. For Cb, n=30 cells; for M1L5, n=15 cells. EPSC, excitatory postsynaptic current.